1. Field of the Invention
The present invention relates to a method of fabricating acoustic transducers, and more particularly to a method of fabricating ferroelectric ultrasonic transducers by using an electton beam.
2. Description of the Prior Art
Ferroelectric acoustic transducers are currently fabricated by placing a thin disk of the ferroelectric material in an oven at the Curie temperature of the ferroelectric. A high DC voltage is imposed on the disk to polarize it and make it acoustically active in a manner similar to piezoelectric crystals. The thickness of the disk determines the resonant frequency of the transducer and damping is determined by a backing member.
The backing member must be impedance matched as closely as possible to the ferroelectric disk to minimize the amplitude of back reflected waves. These back reflected waves result in decreased sensitivity.
For high frequencies (greater than 10 megahertz) a very thin disk is required. However, the ferroelectric materials are very brittle and the thicknesses required to reach these frequencies are very difficult to achieve in useful diameters.